Endothelin-1 (ET-1) is a potent and long-acting vasoconstrictor peptide, which may play a role in the pathophysiology of a number of diseases. Controversial data exist on its role in human ischemic stroke. in order to ascertain whether changes in ET-1 plasma levels occur in ischemic stroke, plasma ET-1 levels and mean arterial pressure were determined in 15 patients at their first ischemic cerebral infarction and in 15 control subjects, over a 24-hour period. In stroke patients, mean 24-hour plasma ET-1 levels (4.9 +/- 0.5 ng/L) were higher (P < 0.05) than in control subjects (3.2 +/- 0.3 ng/L), and correlated with the mean size of the lesion, but not with the severity score of the neurological deficit, These results support the hypothesis that ET-1 levels reflect an indicator function for the amount of damaged cerebral tissue rather than a pathophysiological role. (C) 2001 Editions scientifiques et medicales Elsevier SAS.